Next Step 2 Factory Installed Options Manual
Installation and Operating Instructions
12, 24 Volt Models August 28, 2008



This document covers the factory installed options of the NS2 Regulator, which include the Battery Combiner option, the Two Alternator option, and the Equalization/Serial Port option.

The NS2 Regulator manual should be consulted for background information. In particular, see the wiring diagram in that manual for the parallel solenoid used to combine batteries. Also see the wiring for the remote Error Indicator. All signals are listed in the NS2 Regulator manual.

Another necessary document is the manual for the Remote Access Protocol, RAP.

Battery Combiner Option

The NS2 Battery Combiner Option can independently operate a parallel solenoid to combine batteries to be charged from any charge source at all times. The setpoint where the solenoid closes from any charge source is approximately 13/26 Volts, with the open setpoint about 0.2 Volts below the close setpoint.

Two Alternator Option

The NS2 can be used with a remote module called the Alternator Driver. In a two alternator system the NS2 should be mounted close to one alternator and the Alternator Driver should be mounted close to the other alternator.

Note the OPTIONAL RELAY on the main wiring diagram for the NS2. Though not strictly necessary, use of the relay will prevent field current in the main alternator if the engine isn't being operated. Over the long term, such field current will degrade the rotor winding in an alternator without the fan operating.

There are three signals at the NS2 assoiated with the two alternator option. They are:

See the manual for the Alternator Driver for more information.

Equalization/Serial Port Option

The addition of the serial port allows the NS2 to be controlled from a personal computer, PC. Data can be collected, charge setpoints can be programmed, alternator output can be limited, and battery equalization can be accomplished.

Wiring the Serial Port

To use the serial port the NS2 must be wired to a female DB9 connector. Three wires are required as follows:

A straight thru male/female cable is used to connect the NS2 DB9 to a PC. Many laptops no longer have serial ports, however there are USB-Serial adapters available. Another option is to use a serial to BlueTooth adapter at the NS2 and communicate wirelessly with a PC which has BlueTooth capabilities.

PC Setup to use the Serial Port

The PC requires a program commonly called a Terminal Emulator. All operating systems, (Windows, MacOS, Linux/Unix and others) provide a terminal emulator. On Microsoft platforms the program is called HyperTerminal. It has to be configured with serial port parameters, and assigned a connection port before it operates.

There is no technical assistance available to assist setup, however, there are instructions here: HyperTerminal Setup (

Communications Protocol

A limited implementation of the Remote Access Protocol RAP is included with this option. Enough of RAP was implemented to allow reading data and programming setpoints, although CRC error checking is not implemented.

Also missing is some error checking and qualification of parameters entered by the user. Always verify that the NS2 is operating as expected after programming setpoints.

RAP was principally designed to let another computer talk to Ample Power products. It was purposely designed as an ASCII text protocol to allow easy testing and debugging. While cryptic, it can be used by people. One way to avoid remembering command strings is the generate ASCII files with only commonly used commands and then just download them to the NS2 when necessary.

Before proceeding, acquire a copy of the manual on RAP. One can be downloaded here: RAP Manual, (

The NS2 does not echo characters it receives, however, local echo can be enabled in the terminal emulator to track what has been sent to the NS2.

NS2 Variables and Usage

Name Description Usage
abst absorption time, minutes Read, Set
absv absorption voltage Read, Set
b1t battery temperature Read
b1v battery voltage Read
eqli equalization current, percent Read, Set
eqlt equalization time, minutes Read, Set
eqlv equalization voltage Read, Set
erase erase setpoint Execute
error error code Read, Query
fltv float voltage Read, Set
id NS2 Serial Number Execute
ilim current limit, percent Read, Set
options installed options Read
reg_state regulator state Read, Query
save save setpoint Execute
start_eql start equalization Execute
stop_eql stop equalization Execute
vcal calibration constant Read, Set

In the following example name is to be substituted with the name of a variable listed above. The value field is the value used for setting or querying a variable.

Reading a variable takes the form:


Setting a variable takes the form:


Querying a variable takes the form:


Executing a function takes the form:


ASCII strings which are not entered into the NS2 correctly will generate an error. Errors are described in the RAP Manual.

Querying a Variable

Variables error and reg_state have a numeric value. That numeric value can be translated to a short text message. For instance, querying the reg_state might show the message Absorb indicating the NS2 is presently in the absorption state.

To query a variable, first read it to get its value, and then feed the value back in the form of a query to get the text message.

Programming Setpoints

As configured by the factory, the NS2 uses setpoints based on the potentiometers, pots, that set the absorption voltage, float voltage, and absorption time. It will only use setpoints programmed by the user if user setpoints have first been saved to non-volatile memory. To enable user programmable setpoints, the save function must first be executed. The setpoints from the pots are then saved and the NS2 doesn't monitor the pots anymore. The absv, fltv, and abst variables can now be set as desired.

To revert to setpoints from the pots, the erase function must be executed.

Other programmed setpoints take effect immediately, however, they are not automatically saved to non-volatile memory. To store the setpoints execute the save command. To verify settings were saved to non-volatile memory, momentarily remove power from the NS2 to restart it with the saved settings.

Voltage setpoints must be programmed with two numeric characters following the decimal point, for instance, 14.40.

Current limit setpoints are programmed as a percentage, 0-99. Zero is interpreted as current limit disabled (full current).

Voltage calibration uses the vcal variable. Though not advised, small changes can be made so that battery voltage readings match programmed setpoints. Disconnect the temperature sensor before making this adjustment.

About Current Limiting

The NS2 does duty cycle current limiting. For instance, if the current limit is programmed to 40%, then the NS2 will produce field voltage for up to a maximum of 40% of the time. As a result the alternator will produce about 40% of its output capability. That of course varies with RPM, and to a lesser degree, temperature. Thus a setting of 40% might be 50 Amps at one RPM, and 120 Amps at another. If current limiting is being used while cruising to give more engine power to the prop, set the ilim parameter at the expected RPM.

Equalization current limit is more critical. First, it is generally a very low percentage and engine RPM may not be constant if the engine is just running to equalize batteries.

Expect to tweak current limiting, so monitor the result carefully. Before starting the equalization procedure, program the ilim variable to find out what generates the right amount of battery current. Then program the eqli parameter with the same value.

Equalization Time

Equalization can be stopped at any time by executing the eql_stop function. It will also automatically stop at the end of the programmed time, if not terminated earlier because battery voltage reached the eqlv value. Be sure to set the eqlt before starting the equalization procedure.

For more information about equalization, refer to the two books, Living on 12 Volts with Ample Power and Wiring 12 Volts for Ample Power.

Locking the Setpoint

Strictly speaking, the NS2 doesn't have a lock feature that prevents it from stepping through the float/absorption setpoints. However, both fltv and absv can be set to the same value to effectively lock the regulator.

Ample Power products are manufactured by Ample Technology, 2442 NW Market St., #43, Seattle, WA 98107 - USA